Light-emitting dendrimers

Abstract

Light emitting compounds are disclosed for use in light emitting devices. These compounds have the formula A compound having the formula: CORE [DENTRITE]n in which CORE represents an atom or group, n represents an integer of at least 1 and DENDRITE, which may be the same or different if n is greater than 1, represents an inherently at least partly conjugated dentritic molecular structure comprising aryl and/or heteroaryl groups and alkenyl groups connected to each other via a carbon atom of an alkenyl group to a ring carbon atom of an aryl or heteroaryl group, CORE terminating in the first single bond which is connected to a ring carbon atom of an (hetero)aryl group to which more than one at least partly conjugated dentritic chain is attached, said ring carbon atom forming part of DENDRITE, the CORE and/or DENDRITE being luminescent.

What is claimed is:  
     
       1. A light emitting device incorporating as, or in, its light-emitting element a compound having the formula: 
       
         
           CORE−[DENDRITE] n    
         
       
       in which CORE represents an atom or group, n represents an integer of at least 1 and DENDRITE, which may be the same or different if n is greater than 1, represents an at least partly conjugated dendritic molecular structure comprising groups selected from the group consisting of aryl and heteroaryl groups and alkenyl groups connected to each other via a carbon atom of an alkenyl group to a ring carbon atom of an aryl or heteroaryl group, CORE terminating in a first single bond which is connected to a ring carbon atom of an (hetero)aryl group to which more than one at least partly conjugated dendritic chain is attached, said ring carbon atom of an (hetero)aryl group forming part of DENDRITE, the CORE and/or DENDRITE being luminescent; 
       wherein:  
       (a) the CORE is not                    
        wherein x is bromine or CHO when n=2,  
       (b) the CORE is not bromine or CHO when n=1 and is attached to                    
        and (c) the CORE does not contain the structure  
       
         
           ø t -[—CH═CH-ø p -CH═CH—] 3    
         
       
       in which ø t  is a 1,3,5-bonded benzene ring and ø p  is a para-bonded benzene ring. 
     
     
       2. A device according to  claim 1  which comprises a layer of said compound together with one or more layers of other materials, preferably including or being a hole-transporting or electron-transporting layer. 
     
     
       3. A method of manufacturing a light emitting device of  claim 1  comprising the steps of: 
       (a) providing a film comprising at least one compound having the following formula:  
       
         
           CORE−[DENDRITE] n    
         
       
        in which CORE represents an atom or group, n represents an integer of at least 1 and DENDRITE, which may be the same or different if n is greater than 1, represents an at least partly conjugated dendritic molecular structure comprising groups selected from the group consisting of aryl and heteroaryl groups and alkenyl groups connected to each other via a carbon atom of an alkenyl group to a ring carbon atom of an aryl or heteroaryl group, CORE terminating in a first single bond which is connected to a ring carbon atom of an (hetero)aryl group to which more than one at least partly conjugated dendritic chain is attached, said ring carbon atom of an (hetero)aryl group forming part of DENDRITE, the CORE and/or DENDRITE being luminescent; wherein:  
       (i) the CORE is not                    
        wherein x is bromine or CHO when n=2,  
       (ii) the CORE is not bromine or CHO when n=1 and is attached to                    
        and (iii) the CORE does not contain the structure  
       
         
           ø t -[—CH═CH-ø p -CH═—] 3    
         
       
       in which ø t  is a 1,3,5-bonded benzene ring and ø p  is a para-bonded benzene ring; and, optionally, one or more other films to provide a laminate; 
       (b) adhering to one surface of the film, or where applicable, laminate a substantially transparent electrode; and  
       (c) depositing on another surface of the film, or where applicable, laminate a metallic cathode.  
     
     
       4. The method of  claim 3 , wherein the cathode comprises a metal selected from the group consisting of Al, Mg, Ag, and Ca. 
     
     
       5. A colour display device including pixels comprising one or more light emitting devices of  claim 1 . 
     
     
       6. The colour display device according to  claim 5 , wherein a substantially white or neutral background is provided. 
     
     
       7. A semiconducting device, other than a light emitting device, selected from the group consisting of photodiodes, solar cells, FETs, and solid state triodes, wherein the semiconducting device comprises a compound having the following formula: 
       
         
           CORE−[DENDRITE] n    
         
       
       in which CORE represents an atom or group , n represents an integer of at least 1 and DENDRITE, which may be the same or different if n is greater than 1, represents an at least partly conjugated dendritic molecular structure comprising groups selected from the group consisting of aryl and heteroaryl groups and alkenyl groups connected to each other via a carbon atom of an alkenyl group to a ring carbon atom of an aryl or heteroaryl group, CORE terminating in a first single bond which is connected to a ring carbon atom of an (hetero)aryl group to which more than one at least partly conjugated dendritic chain is attached, said ring carbon atom of an (hetero)aryl group forming part of DENDRITE, the CORE and/or DENDRITE being luminescent; wherein: 
       (i) the CORE is not                    
        wherein x is bromine or CHO when n=2,  
       (ii) the CORE is not bromine or CHO when n=1 and is attached to                    
        and (iii) the CORE does not contain the structure  
       
         
           ø t -[—CH═CH-ø p -CH═CH—] 3    
         
       
       in which ø t  is a 1,3,5-bonded benzene ring and ø p  is para-bonded benzene ring. 
     
     
       8. A film formed of a compound having the following formula: 
       
         
           CORE−[DENDRITE] n    
         
       
       in which CORE represents an atom or group, n represents an integer of at least 1 and DENDRITE, which may be the same or different if n is greater than 1, represents an at least partly conjugated dendritic molecular structure comprising groups selected from the group consisting of aryl and heteroaryl groups and alkenyl groups connected to each other via a carbon atom of an alkenyl group to a ring carbon atom of an aryl or heteroaryl group, CORE terminating in a first single bond which is connected to a ring carbon of an (hetero)aryl group to which more than one at least partly conjugated dendritic chain is attached, said ring carbon atom of an (hetero)aryl group forming part of DENDRITE, the CORE and/or DENDRITE being luminescent; wherein: 
       (i) the CORE is not                    
        wherein x is bromine or CHO when n=2,  
       (ii) the CORE is not bromine or CHO when n=1 and is attached to                    
        and (iii) the CORE does not contain the structure  
       ti ø t -[—CH═CH-ø p -CH═CH—] 3    
       in which ø t  is a 1,3,5-bonded benzene ring and ø p  is a para-bonded benzene ring. 
     
     
       9. The film of  claim 8 , wherein the film has a thickness of between 20 to 200 nanometres, more preferably 50 to 150 nanometres. 
     
     
       10. The film of  claim 9  in a mixture with a film-forming polymeric material or binder.